Electrical fuse



1,681,240 C. A. JOHNSON ET AL i ELECTRICAL EUsE Aug. 21, 192s.

Filed Jan. 29,` 1925 Patented Ausg.v 2l, 1928.

UNITED STATES PATENT OFFICE.

CHESTER JOHNSON AND HERVEY DANA. HARLAND', OF' CEICA'GO, ILLINOIS, AS- SIGNORS TO CHICAGO FUSE MFG. COMPANY, OF CHICAGO, ILLINOIS, A CORPORA- TION OF ILLINOIS.

ELECTRICAL FUSE.

Application filed January 29, 1925. Serial No.'5,427.

Our invention relates to improvements in electric fuses and more specifically to fuses for carrying small currents such as are utilized in heating the filaments of radio vacuum tubes.

One object ot' the invention is to provide an electrical fuse of new and improved construction in which the Jfuse element is supported within a transparent protecting dome. y

vAnother object is to provide an inexpensive fuse cartridge havinglspace'd Contact members to which a delicate fuse element in the form of a fine wire can be conveniently attached as by soldering.

A further object is to provide a fuse cartridge which has external contactu legs eX- tending perpendicular to and projecting laterally from one end of the cartridge case.

A still further object is to provide a complete radio fuse unit adapted to be mounted perpendicularly upon an insulatingy base, said unit including a detachable fuse cartridge mounted on two spaced binding posts.

Other objects and advantages will become apparent from the following description. v lVhile we have shown in the drawings and will herein describe in detail the preferred embodiment of the invention, it is to be understood' that such disclosure is made merely for the purpose of illustration and that other modifications and variations will probably occurfto thosev skilled in the art. In the appended claims we aim to'cover all modifications and variations falling within the spirit and scope of the invention.

In the drawings Figure 1 is an enlargedv vertical sectional view of a fuse unit embodying the features' ofourinvention.

Fig. 2 is a perspective vievs7 of the fuse cartridge. f

Referring to the exemplary embodiment of. the invention, 10. represents a pair of metallic contact members which are mounted in a suitable insulating plug 11 and adapted to support a suitable fuse element 12. The plug 11 Amay consist of a plurality of disks of fibrous material formed with rectangular apertures which provide vertical holes 13 in the plugJ,`

Preferably, each member 10 is Lishaped and has a fuse-supporting leg 14 and a con- I tact'leg 15.- 'To firmly hold the fuse-supporting legs 14C in opposed relatiom'each is 55 torced through one of the holes 13 in the plug until its contact leg 15 abuts the underside of the plug. With the legs thus postioned, a fuse element 12 in the form ot a fine fusible wire may be placed acrossthe 6o upper ends of the legs and conveniently attached thereto by soldering. A notch 16 may be provided in each fuse-supporting leg 14 to assist in holding the fuse element in position for soldering; Y

To enclose and protect the fuse element 12, a case 17 preferably in the form of a lcylindrical transparent dome is provided..

Theopen end of the case may be fitted snug ly over the plug 11 and cemented thereto if 70 desired.

When the fuse-supporting legs 14 are thus supported vertically in the plug 11, the contact legs 15 will project laterally in oppositel directions from the lower end of the case 17. These legs are preferably fiat and considerably wider 'than the fuse-supporting legs 14. They may be of any desired shape. Inthe form shown in Fig. 2, the leg 15a has a bifurcated end 18 providing a longitudinal 80 recess 19 while the leg 15b has a hooked end 20 providing a lateral recess 21. This ar-l rangement, it will be later observed, facilitates attachment of the contact legs 15 between spaced binding` posts such as are 85 shown in Figure 1.-

l It will be apparent that the elements thus assembledandshown particularly in Fig. 2 constitute a complete fuse cartridge which is extremely simple and inexpensive to construct. The delicate fuse element 12 is' well protected from injury and its condition is always plainly observable. The fuse is therefore particularly adapted for use in circuits utilizing small currents where abloW can be detected only by observing the condii tion of the fuse element.

Suitable means such as spaced binding posts 22 is provided for' mounting thefuse cartridge.' In Figure 1 each binding post 100 comprises a screw bolt 23 mounted on an insulating board 24 and having a contact plate 25 threaded onto the bolt 23 and a thumb nut 26 between which one of the contact legs 15 of the cartridge may be firmly clamped. 105 To facilitate attachment of the leadl Wires 27, plates 28'having inclined rojections 29 may also be provided on the indng posts.

In mounting the fuse cartridge, the bifurcated end 18 of the contact leg l5a is first placed against one ofthe binding posts between the Contact plate 25 and the nut 2G. `With that binding post as a pivot, the hooked end l5 may be swung into engagement with the other binding post and the thumb nuts 26 then tightened. The cartridge will thus be rigidly supported in upright position in good electrical contact with the lead wires. It may be conveniently and quickly replaced in case of a blow.

Ve claim as our invention.

l. An electrical fuse comprising, in conibination, a transparent case having an insulating plug closing the end thereof. and two L-shaped metallic stri ps each having one leg passing through an aperture in said plug into the space within said case, the inner ends of the latter legs being joined by a fuse element, the other legs of said strips projecting laterally. from said case to provide external contacts.

2. An electrical fuse comprising, in combination, a transparent dome, an insulating plug -fitting in the end of said dome, two metallic members each having two legs one extending at right angles to the other, one leg of eachl member being passed through said plug to provide parallel fuse supports Within the dome, the ends of said supports being connected by a fusible element, the other legs of said members projecting outwardly from the periphery ot said dome to provide contact terminals on opposite sides thereof.

3. An electrical fuse comprising, in coin-v bination, a pair of metallic members each having fuse-supporting and Contact legs, an insulating member through which said fuse supporting legs extend and by which the fuse-supporting legs are held in opposed relation, a fusible element attached to the latter legs, and a dome enclosing said element and said supporting legs, said contact legs abutting against said insulating member and projecting outwardly beyond the periphery of said dome.

4. An electrical fuse comprising7 in combination, a hollow case, a pair of Contact members cach comprising two legs, one leg of each member projecting into the hollow portion of said case, a fuse element joining the last mentioned legs Within said case, the other legs ot said members projecting laterally from said case to provide contact terminals ati' their ends.

In testimony whereof wehave hereunto atixed our signatures.

HERVEY nana HARLAND. CHESTER a. JoHNsoN.

esauriente or connection man No. 1,681,240.

CHESTER A. JoHNsoN ET AL.

. It 'is hereby certified that `the above numbered patent waserroneously issued -to "Chicago Fuse Mfg. Company, of Chicago, Illinois, a Corporation of illinois", whereas said patent should have been issued to "Chicago Jefferson Fuse &,Electric Company, oi Chicago,- Illinois,' aCorporation of Illinoisf, said corporation being assigne of the entire interestin said invention, as` shown Aby the records of assignments in this office"; and that the said Letters Patent should be read with this correction therein that the samemay conform to the record of thecase inthe een ome.

signed and sealed :his am day'of November, A, D. 192s.-

(Sul) j M; J. Moore, Acting Commissioner of Patents: 

